Today, MacRumors received a tip from a developer that he found a single instance of iPhone OS 4.0 being used in his application’s Pinch Media analytics data.

iPhone OS 3.1.3 may release very soon and is expected to be a minor firmware update and bug fixes but on the other hand iPhone Firmware 4.0 would be a major release and is expected to be shipped with the next-gen iPhone the coming Summer.

There is no info on iPhone OS 4.0 features but it’ll surely brought us more features just like iPhone firmware 3.0 did.